1. The Field of the Invention
This invention relates to continuity and insulation breakdown testing devices and more particularly to that class adapted to evaluate two terminal devices, one of which is grounded to a chassis of a vehicle.
2. Description of the Prior Art
The prior art abounds with continuity and voltage breakdown devices. My Canadian Pat. No. 992,611 dated July 6, 1976 discloses a car antenna tester utilizing a pair of clamps, one of which is adapted for connection to an antenna shield, the other of which is adapted for connection to an antenna. Three battery supplies are electrically interconnected to a triple pole single throw switch, each pole of which being individually connected to a pair of incandescent lamps and a neon lamp. An antenna jack is provided which is electrically connected to a plug fitted at one end of the lead wire coupled to the antenna. When the switch is closed, the continuity of the shield wire may be evaluated by judicious selective attachment of one of the clamps to the shielding conductor. In similar fashion, the other clamp determines the electrical continuity of the isolated conductor in the lead wire feeding the antenna. However, the device as disclosed, may constitute a shock hazard when the neon lamp interconnected with its individual high voltage battery supply to the pair of clamps, ionizes. Furthermore, the apparatus fails to provide a suitable arrangement for bench testing an antenna connected to a lead cable before installation in the vehicle, and fails to provide for the installed testing of an antenna and lead wire wherein the shielding conductor of the lead wire is not grounded as part of a normal installation.
U.S. Pat. No. 2,229,927 issued on Jan. 28, 1941 to J. A. Kamper teaches three indicating lamps, two of which are connected in a series electrical circuit terminating across a pair of electrical clamps. The third lamp bridges the electrical clamps. A probe wire is electrically connected at the junction of the pair of lamps in the series circuit. This device, devoid of internal source of energy is particularly useful in checking the electrical systems of motor vehicles and the like, utilizing the battery supply of the vehicle as a power source for illuminating the test lamps so as to dynamically present visual indications of the status of the electrical circuitry of the motor vehicle, in regard to the continuity and the shorting between the electrical elements thereof.